A battery consists of one or more electrochemical cells, wherein each cell typically includes a positive electrode, a negative electrode, and an electrolyte or other material for facilitating movement of ionic charge carriers between the negative electrode and positive electrode. As the cell is charged, cations migrate from the positive electrode to the electrolyte and, concurrently, from the electrolyte to the negative electrode. During discharge, cations migrate from the negative electrode to the electrolyte and, concurrently, from the electrolyte to the positive electrode.
Such batteries generally include an electrochemically active material having a crystal lattice structure or framework from which ions can be extracted and subsequently reinserted, and/or permit ions to be inserted or intercalated and subsequently extracted.
Recently, three-dimensionally structured compounds comprising polyanions (e.g., (SO4)n−, (PO4)n−, (AsO4)n−, and the like), have been devised as viable alternatives to oxide-based electrode materials such as LiMxOy. Examples of such polyanion-based materials include the ordered olivine LiMPO4 compounds, wherein M=Mn, Fe, Co or the like. Other examples of such polyanion-based materials include the NASICON Li3M2(PO4)3 compounds, wherein M=Mn, Fe, Co or the like. Although these classes of lithiated polyanion-based compounds have exhibited some promise as electrode components, many such polyanion-based materials are not economical to produce, afford insufficient voltage, have insufficient charge capacity, exhibit low ionic and/or electrical conductivity, or lose their ability to be recharged over multiple cycles. Therefore, there is a current need for an electrode active material that exhibits greater charge capacity, is economical to produce, affords sufficient voltage, exhibits greater ionic and electrical conductivity, and retains capacity over multiple cycles.